table.c revision 311751 
1/*
2 * Copyright (c) 1983, 1993
3 *	The Regents of the University of California.  All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 *    notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 *    notice, this list of conditions and the following disclaimer in the
12 *    documentation and/or other materials provided with the distribution.
13 * 3. Neither the name of the University nor the names of its contributors
14 *    may be used to endorse or promote products derived from this software
15 *    without specific prior written permission.
16 *
17 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
18 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
19 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
20 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
21 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
22 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
23 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
24 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
25 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
26 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
27 * SUCH DAMAGE.
28 */
29
30#ifndef lint
31#if 0
32static char sccsid[] = "@(#)table.c	8.1 (Berkeley) 6/4/93";
33#endif
34static const char rcsid[] =
35  "$FreeBSD: stable/10/libexec/talkd/table.c 311751 2017-01-09 05:52:30Z delphij $";
36#endif /* not lint */
37
38/*
39 * Routines to handle insertion, deletion, etc on the table
40 * of requests kept by the daemon. Nothing fancy here, linear
41 * search on a double-linked list. A time is kept with each
42 * entry so that overly old invitations can be eliminated.
43 *
44 * Consider this a mis-guided attempt at modularity
45 */
46#include <sys/param.h>
47#include <sys/time.h>
48#include <sys/socket.h>
49#include <netinet/in.h>
50#include <protocols/talkd.h>
51#include <stdio.h>
52#include <stdlib.h>
53#include <string.h>
54#include <syslog.h>
55#include <unistd.h>
56
57#include "extern.h"
58
59#define MAX_ID 16000	/* << 2^15 so I don't have sign troubles */
60
61#define NIL ((TABLE_ENTRY *)0)
62
63static struct timespec ts;
64
65typedef struct table_entry TABLE_ENTRY;
66
67struct table_entry {
68	CTL_MSG request;
69	long	time;
70	TABLE_ENTRY *next;
71	TABLE_ENTRY *last;
72};
73
74static void delete(TABLE_ENTRY *);
75
76static TABLE_ENTRY *table = NIL;
77
78/*
79 * Look in the table for an invitation that matches the current
80 * request looking for an invitation
81 */
82CTL_MSG *
83find_match(CTL_MSG *request)
84{
85	TABLE_ENTRY *ptr, *next;
86	time_t current_time;
87
88	clock_gettime(CLOCK_MONOTONIC_FAST, &ts);
89	current_time = ts.tv_sec;
90	if (debug)
91		print_request("find_match", request);
92	for (ptr = table; ptr != NIL; ptr = next) {
93		next = ptr->next;
94		if ((ptr->time - current_time) > MAX_LIFE) {
95			/* the entry is too old */
96			if (debug)
97				print_request("deleting expired entry",
98				    &ptr->request);
99			delete(ptr);
100			continue;
101		}
102		if (debug)
103			print_request("", &ptr->request);
104		if (strcmp(request->l_name, ptr->request.r_name) == 0 &&
105		    strcmp(request->r_name, ptr->request.l_name) == 0 &&
106		     ptr->request.type == LEAVE_INVITE)
107			return (&ptr->request);
108	}
109	return ((CTL_MSG *)0);
110}
111
112/*
113 * Look for an identical request, as opposed to a complimentary
114 * one as find_match does
115 */
116CTL_MSG *
117find_request(CTL_MSG *request)
118{
119	TABLE_ENTRY *ptr, *next;
120	time_t current_time;
121
122	clock_gettime(CLOCK_MONOTONIC_FAST, &ts);
123	current_time = ts.tv_sec;
124	/*
125	 * See if this is a repeated message, and check for
126	 * out of date entries in the table while we are it.
127	 */
128	if (debug)
129		print_request("find_request", request);
130	for (ptr = table; ptr != NIL; ptr = next) {
131		next = ptr->next;
132		if ((ptr->time - current_time) > MAX_LIFE) {
133			/* the entry is too old */
134			if (debug)
135				print_request("deleting expired entry",
136				    &ptr->request);
137			delete(ptr);
138			continue;
139		}
140		if (debug)
141			print_request("", &ptr->request);
142		if (strcmp(request->r_name, ptr->request.r_name) == 0 &&
143		    strcmp(request->l_name, ptr->request.l_name) == 0 &&
144		    request->type == ptr->request.type &&
145		    request->pid == ptr->request.pid) {
146			/* update the time if we 'touch' it */
147			ptr->time = current_time;
148			return (&ptr->request);
149		}
150	}
151	return ((CTL_MSG *)0);
152}
153
154void
155insert_table(CTL_MSG *request, CTL_RESPONSE *response)
156{
157	TABLE_ENTRY *ptr;
158	time_t current_time;
159
160	clock_gettime(CLOCK_MONOTONIC_FAST, &ts);
161	current_time = ts.tv_sec;
162	request->id_num = new_id();
163	response->id_num = htonl(request->id_num);
164	/* insert a new entry into the top of the list */
165	ptr = (TABLE_ENTRY *)malloc(sizeof(TABLE_ENTRY));
166	if (ptr == NIL) {
167		syslog(LOG_ERR, "insert_table: Out of memory");
168		_exit(1);
169	}
170	ptr->time = current_time;
171	ptr->request = *request;
172	ptr->next = table;
173	if (ptr->next != NIL)
174		ptr->next->last = ptr;
175	ptr->last = NIL;
176	table = ptr;
177}
178
179/*
180 * Generate a unique non-zero sequence number
181 */
182int
183new_id(void)
184{
185	static int current_id = 0;
186
187	current_id = (current_id + 1) % MAX_ID;
188	/* 0 is reserved, helps to pick up bugs */
189	if (current_id == 0)
190		current_id = 1;
191	return (current_id);
192}
193
194/*
195 * Delete the invitation with id 'id_num'
196 */
197int
198delete_invite(u_int32_t id_num)
199{
200	TABLE_ENTRY *ptr;
201
202	ptr = table;
203	if (debug)
204		syslog(LOG_DEBUG, "delete_invite(%d)", id_num);
205	for (ptr = table; ptr != NIL; ptr = ptr->next) {
206		if (ptr->request.id_num == id_num)
207			break;
208		if (debug)
209			print_request("", &ptr->request);
210	}
211	if (ptr != NIL) {
212		delete(ptr);
213		return (SUCCESS);
214	}
215	return (NOT_HERE);
216}
217
218/*
219 * Classic delete from a double-linked list
220 */
221static void
222delete(TABLE_ENTRY *ptr)
223{
224
225	if (debug)
226		print_request("delete", &ptr->request);
227	if (table == ptr)
228		table = ptr->next;
229	else if (ptr->last != NIL)
230		ptr->last->next = ptr->next;
231	if (ptr->next != NIL)
232		ptr->next->last = ptr->last;
233	free((char *)ptr);
234}
235